Electromagnetic device for electric-circuit control and protection systems



Dec. 29, 1910 v, A, SMIRNQV ET AL ELECTROMAGNETIC DEVICE FORELECTRIC-CIRCUIT CONTROL AND PROTECTION SYSTEMS Filed Nov. 20, 1968 FiGiUnited States Patent 3,551,860 ELECTROMAGNETIC DEVICE FOR ELECTRIC.CIRCUIT CONTROL AND PROTECTION SYSTEMS Vladimir Alexeevich Smirnov, Ul.Panfilova 20, korp.

2, kv. 128, and Vadim Nikolaevich Shoifa, 1 Dubrovskaya ul. 6a, kv. 11,both of Moscow, U.S.S.R.

Filed Nov. 20, 1968, Ser. No. 777,380 Claims priority, applicationU.S.S.R., Nov. 23, 1967,

,195,561 Int. Cl. HOlh 1/6'6 US. Cl. 335-151 Claims ABSTRACT OF THEDISCLOSURE An electromagnetic device for electric-circuit control andprotection systems, comprising elastically mounted magneticallycontrolled long cores whose overlapping free ends are arranged with acertain air gap relative to each other when the magnetizing coil isdeenergized so that in the case of a rising magnetic field around themagnetizing coil the magnetically controlled cores first come closertogether until they reach a certain air gap between them, and then moveapart before they completely close, which makes it possible to use saiddevice as an adjustable capacitance and also for electric-circuitswitching. In the latter case the device is provided with contact tipsor springs.

The present invention relates to elements used in electric-circuitcontrol and protection systems, and more specifically to anelectromagnetic device.

There exists a similar electromagnetic device comprising elasticallymounted magnetically controlled long cores which are permanentlyanchored at one end, while their opposite contact ends, overlapping whenthe coil surrounding them is de-encrgized, are arranged with a certaininitial air gap relative to one another.

In the electromagnetic device just cited, the contact ends of themagnetically controlled cores have an initial air gap between them, suchthat an increase in the current flowing through the coil causes them toclose and remain closed as the coil current continues to rise, while theopening of the contacts (the separation of the magnetically operatedcores) can take place only when the current through the coil decreases.

In some electric circuits, however, when the device is, for example,used as an adjustable capacitance, it is preferable that themagnetically controlled cores should separate not only with a decreaseof current through the magnetizing coil, but also with an increase ofcurrent, which the device just quoted does not provide for.

An object of the present invention is to eliminate the above-mentioneddisadvantage.

A specific object of the invention is to provide an electromagneticdevice for electric-circuit control and protection systems in which themagnetically controlled core-s operate in such a manner that theyseparate after they have come closer together not only with a decreaseof current in the magnetizing coil, but also with an increase ofcurrent.

This object is accomplished by the fact that in an elec tromagneticdevice comprising elastically mounted magnetically controlled long coreswhose overlapping free ends are arranged with a certain air gap relativeto one another when the magnetizing coil is de-energized, themagnetically controlled cores have, according to the invention, theirfree ends separated from one another by a distance exceeding the maximumgap necessary for the magnetically controlled cores to make in a risingmagnetic field around the magnetizing coil, but smaller than thedistance at which the eiiective magnetic action of the said coresceases, so that in the case of a rising magnetic field around themagnetizing coil the magnetically controlled cores first come closertogether until they reach a certain minimum air gap between them, andthen move apart before they completely close.

In order to adapt the device disclosed herein to switch electriccircuits, the overlapping portions of the magnetically controlled coresmay have contact tips on their inward-facing surfaces, the totalthickness of these tips being sufficient for the cores to make when theycome closest to one another.

For the same purpose the free ends of the magnetically controlled coresmay have notches on their inward-facing portions, so that the ends ofadditional non-magnetic contact springs may enter the notches with acertain air gap. In such a case, the number of circuits that can beswitched by the device disclosed herein is increased.

For the purpose of adjusting the air gap between the magneticallycontrolled cores and the additional nonmagnetic contact springs, it ispreferable to provide nonmagnetic elements with non-metallic eccentrics.

The electromagnetic device embodied in accordance with the presentinvention accomplishes the objective of the invention and may be used asan adjustable capacitance whose value first increases as the current inthe magnetizing coil increases from zero, and then decreases, and alsofor electric-circuit switching.

The invention will be best understood from the following description ofpreferred embodiments, when read in connection with the accompanyingdrawings in which:

FIG. 1 is a general sketch of an electromagnetic device, according tothe invention;

FIG. 2 shows the inward-facing overlapping ends of the magneticallycontrolled cores of the device of FIG. 1, with contact tips, adapted toswitch one electric circuit, and

FIG. 3 is a general sketch of an electromagnetic device adapted toswitch two electric circuits.

Referring to FIG. 1, therein is shown an electromagnetic devicecomprising a magnetizing coil 1 arranged on a cylindrical former 2 withinsulating ends 3 and 4, inside which there are magnetically controlledferromagnetic cores 5 and 6. The outer ends of the cores 5 and 6 arepermanently anchored in the ends 3 and 4 of the former 2, while theinner overlapping ends are arranged with a certain air gap relative toone another.

The air gap 6 is chosen so that it slightly exceeds the maximum air gapnecessary for the magnetically controlled cores to close as in existingdevices, but smaller than the distance at which the effective magneticinteraction between the cores 5 and 6 ceases.

The electromagnetic device disclosed herein operates as follows.

When the magnetizing coil 1 is energized, two magnetic fluxes thread themagnetically controlled cores 5 and 6. The first magnetic flux, shown bythe dash-dot line in FIG. 1, threads both magnetically controlled cores5 and 6 and, on passing through the air gap between the cores at theoverlap, gives rise to an electromagnetic force of attraction betweenthe magnetically controlled cores 5 and 6'. The second magnetic flux,shown by the dashed line in FIG. 1, threads separately each of themagnetically controlled cores 5 and 6, giving rise to an electromagneticforce tending to move the cores 5 and 6 apart.

As the current through the magnetizing coil 1 increases, themagnetically controlled cores 5 and 6 first move towards each otheruntil they reach a certain minimum air-gap between them, and, as thecurrent continues to rise, become saturated outside the overlap. As thishappens, the first magnetic flux rises insignificantly,

The second magnetic flux, which threads the overlap through the portionsof the magnetically controlled cores and 6 with a smaller value ofmagnetic induction, grows more. This brings about a decrease in theresultant electromagnetic force which causes the magnetically controlledcores 5 and 6 to move closer together, with the result that they moveapart. As the current through the magnetizing coil 1 rises still more,the magnetically controlled cores 5 and 6 move farther apart.

Referring to FIG. 2, in an electromagnetic device adapted to switch anelectric circuit, the overlapping ends of the magnetically controlledcores 5 and 6 have nonmagnetic contact tips 7 and 8 on theirinward-facing surfaces, the total thickness of these tips being not lessthan the minimum air gap within which the cores 5 and 6 may approacheach other as the current in the magnetizing coil 1 increases.

In such a case, the magnetically controlled cores 5 and 6 first close asthe current in the coil 1 increases, and then open as the currentcontinues to rise.

In order to increase the number of electric circuits that can beswitched by the device disclosed herein, instead of contact tips, thefree ends of the cores 5 and 6 may have notches on their inward-facingfree portions, the notches being such that they receive the free ends ofadditional non-magnetic contact springs 9 and .10 (FIG. 3) with acertain air gap, while the other ends of the said contact springs arepermanently anchored in the ends 3 and 4 of the former 2.

For the purpose of adjusting the air gap 'between the notches in themagnetically controlled cores 5 and 6 and the ends of the contactsprings 9 and 10 entering them, the device disclosed herein hasnon-magnetic rods 11 and 12 with threaded ends which are screwed intocouplers 13 and 14 made fast in the ends 3 and 4 of the former 2, whilethe elongated portion of the said rods carry metallic eccentrics 15 and16.

Rotation of the rods 11 and 12 causes the eccentrics 15 and 16 to rotatetoo, thereby varying the said air gap.

What is claimed is:

1. An electromagnetic device for electric-circuit control and protectionsystems, comprising: a magnetizing coil; elastically mountedmagnetically controlled long cores having overlapping free ends embracedby said magnetizing coil and means separating said cores, with 4 saidcoil deenergized, by a distance exceeding the maximum gap for which saidmagnetically controlled cores make contact in a rising magnetic fieldaround said magnetizing coil, but smaller than the distance at which theeffective magnetic interaction between said cores ceases, so that in thecase of a rising magnetic field around said magnetizing coil, saidmagnetically controlled cores first move closer together until theyreach a certain minimum air gap, and then separate before theycompletely close.

2. An electromagnetic device, as claimed in claim 1, in which theoverlapping portions of said magnetically controlled cores includenon-magnetic contact tips on the inward-facing surfaces, the totalthickness of said contact tips being suflicient for said magneticallycontrolled cores to make when they come closest to each other as thefield around said magnetizing coil builds up.

3. An electromagnetic device, as claimed in claim 1, in which theoverlapping portions of said magnetically controlled cores have notcheson their inward-facing surfaces, and comprising additional non-magneticcontact springs with ends which enter said notches with a certainair-gap.

4. An electromagnetic device, as claimed in claim 3, comprisingnon-magnetic elements with non-metallic eccentrics between said coil andsaid additional non-magnetic contact springs for adjusting the air gapbetween said megnetically controlled cores and said additionalnon-magnetic contact springs.

'5. An electromagnetic device as claimed in claim 1 comprisingnon-magnetic contact members interposed between facing surfaces of saidcores to provide closed circuit when the cores first move closertogether and reach the minimum air gap.

References Cited UNITED STATES PATENTS 3,075,059 1/1963 Blaha et al.335-153 3,462,718 8/1969 Takei 335-154 BERNARD A. GILHEANY, PrimaryExaminer R. N. ENVALL, 1a., Assistant Examiner U.S. c1. XtR. 317-449

